One-degree-of-freedom motion induced by modeled vortex shedding

The motion of an elastically supported cylinder forced by a nonlinear, quasi-static, aerodynamic model with the unusual feature of a motion-dependent forcing frequency was studied. Numerical solutions for the motion and the Lyapunov exponents are presented for three forcing amplitudes and two frequencies (1.0 and 1.1 times the Strouhal frequency). Initially, positive Lyapunov exponents occur and the motion can appear chaotic. After thousands of characteristic times, the motion changes to a motion (verified analytically) that is periodic and damped. This periodic, damped motion was not observed experimentally, thus raising questions concerning the modeling

Lessons Learned from the U.S. Department of Energy's Motor Challenge Showcase Demonstration Projects

This paper presents a summary of the practical lessons learned to date from the U.S. Department of Energy's (DOE) Showcase Demonstration Projects. These projects are part of the DOE Motor Challenge Program, and are aimed at demonstrating increased electric motor system efficiency through the integration of a variety of technology and applications options. These include: energy efficient electric motors, adjustable speed drives, and motor-driven equipment (e.g., pumps, fans, and compressors) within industrial operations and processes. Each Showcase Project is made up of a team that consists of a host demonstration site and supporting partners (e.g. utilities, motor and process equipment suppliers, and contractors). Each team is expected to provide DOE with sufficient data to substantiate and document the energy and environmental performance of the project and the economic cost/benefit of the results. Additionally, teams provide appropriate information to DOE to allow DOE contractors to perform an independent performance validation report and to prepare a comprehensive case study document. DOE provides each Showcase Team access to technical experts who will assist on questions which may arise during the course of the project. DOE also sponsors workshops to allow Showcase teams to exchange information and discuss lessons learned. At the conclusion of each project DOE publishes and distributes a comprehensive case study document. Papers presented at this conference in 1996 and 1997 gave a description and status of the projects that were selected to be Motor Challenge Showcases. This paper will concentrate on the Showcases that have been completed and the important lessons learned

Status of the U.S. Department of Energy's Motor Challenge Showcase Demonstration Projects

This paper describes the status of the U.S. Department of Energy's (DOE) Showcase Demonstration Projects. These projects are part of the DOE Motor Challenge Program, and are aimed at demonstrating increased electric motor system efficiency through the integration of a variety of technology and applications options. These include: energy efficient electric motors, adjustable speed drives, and motor-driven equipment (e.g., pumps, fans, and compressors) within industrial operations and processes. Each Showcase Project team consists of a host demonstration site and supporting partners (e.g. utilities, motor and process equipment suppliers, and contractors). Each team is expected to provide DOE with sufficient data to substantiate and document the energy and environmental performance of the project and the economic cost/benefit of the results. Additionally, teams will provide appropriate information to DOE to allow for DOE contractors to perform an independent performance validation report and to prepare a comprehensive case study document. DOE provides each Showcase Team access to technical experts who will assist on questions which may arise during the course of the project. DOE will also sponsor special workshops to allow Showcase teams to exchange information and discuss lessons learned. At the conclusion of each project DOE will publish and distribute a comprehensive case history document. This paper presents the status of the projects, the results of the independent performance validation, and the lessons learned to date

Variability in fatty acids composition in eggs of an omnivorous waterbird, the black-headed gull Chroicocephalus ridibundus, foraging in different habitats

AbstractAnalysis of the qualitative signature of fatty acids in tissues of organisms is an increasingly utilized tool in studies of trophic ecology in aquatic and terrestrial ecosystems. Here, we studied a colonial waterbird, the black-headed gull Chroicocephalus ridibundus, nesting in three colonies. We aimed to investigate whether fatty acid composition of its eggs is affected by the location of the colony (reflecting the spatial variation in habitat composition and, in turn, female diet at the time of egg formation), and the egg laying sequence (reflecting the temporal variation in female diet). We found that the composition of fatty acids in eggs of black-headed gulls differed among colonies, but not among subsequent eggs within the clutch. We interpret these results in the context of spatial differences in the diet of females breeding in different colonies and a lack of temporal variation in the diet of individual females. The pattern of the ratio of omega-3 to omega-6 fatty acids reflected the contribution of aquatic/terrestrial prey to their diet, and was consistent with the area of water courses around the colonies. High levels of omega-6:omega-3 can promote inflammation and thus lead to increased susceptibility to antigens. Further studies with prey sampling are required to reconstruct the diet composition of females during egg formation in more detail

The role of the secondary dust emission in the semirecreational area in the exposure of the human population of compounds Ni, Fe, Cu and Zn

Zawartość Ni, Fe, Cu, Zn w powietrzu, glebie i opadach w centrum Zawoi oznaczono metodą ICP-AES. Pobór imisji tych metali wykonano za pomocą pyłomierza stałego kierunkowego i ruchomego w sąsiedztwie ulicy i odległości 200m od ulicy. Zjawisko wtórnego pylenia opisano za pomocą współczynników kontaminacji Endler’a, współczynnika wtórnej emisji Steward’a, współczynnika wzbogacenia Endler’a. Dodatkowy udział tego zjawiska i ogólną zawartość metali w przyziemnej warstwie powietrza określono według Szymczykiewicza. Stanowisko Markowe Szczawiny (Babia Góra) może być wykorzystane w badaniach prospektywnych jako układ odniesienia jakości powietrza. Na terenach semirekreacyjnych znaczący okresowy dodatkowy udział ma wtórna emisja pyłów. Współczynniki kontaminacji Endler’a (dwie wersje) oraz Szymczykiewicza i Steward’a dobrze charakteryzują względną zmianę jakości powietrza w sąsiedztwie powierzchni utwardzonych i w funkcji odległości od ruchliwej ulicy.The content of Ni, Fe, Cu, Zn in the air, soil and rainfall was determined by ICP-AES. The consumption of the imissions of these metals was performed using the fixed and moving direction dust meter in the vicinity of the street and at the distance 200m from the street. The phenomenon of the secondary dust emission was described using Endler’s coefficients contamination, the Steward's coefficient of secondary emission and the Endler’s enrichment factor. The additional part of this phenomenon and the overall content of metals in the ground layer of air was determined by Szymczykiewicz. The position Markowe Szczawiny (Babia Mountain) can be used in prospective studies as a reference air quality. In semirecreational areas the secondary dust emission has influence on the additional significant periodic. The coefficients of contamination of Endler’s (two versions), Szymczykiewicz and Steward’s feature relative change in the air quality in the vicinity of the surface hardened and in the distance function from the busy street

The Evaluation of the Heart Failure Patient by Echocardiography: Time to go beyond the Ejection Fraction

Heart failure is a complex clinical syndrome that can result from any structural or functional cardiac disorder that impairs the ability of the ventricle to fill with or eject blood. The echocardiogram is the single most performed and useful study in these patients. This article reviews the role of the echocardiogram in the evaluation of the heart failure patient, without focusing on the left ventricle. The discussion includes the use of the echocardiogram in the assessment of the right ventricle and diastolic function and in detecting hemodynamic and morphologic changes in heart failure over a period of time. In addition, we highlight some of the limitations of echocardiography in the assessment of these patients

Continuous Flow Left Ventricular Assist Device Therapy: A Focused Review on Optimal Patient Selection and Long-Term Follow-up Using Echocardiography

Despite widespread awareness and use of scientifically proven life-prolonging medical and device-based therapies over the last two decades, heart failure remains a leading cause of morbidity, mortality, and health care expenditure in the United States. Mechanical circulatory support with a continuous-flow left ventricular assist device (CF-LVAD), either as a bridge to heart transplantation or as destination therapy, is an increasingly used treatment modality for patients with advanced heart failure syndromes that worsen despite their receiving standard therapies. CF-LVAD support creates unique hemodynamic alterations that must be understood to provide appropriate care for these patients before and after implantation. Echocardiography is essential in the evaluation of patients who are being considered for or are mechanically supported by CF-LVADs. Here we provide a focused clinical review on the use of echocardiography in two main aspects of the evaluation of these patients: (a) optimal patient selection for CF-LVAD support and (b) follow-up assessment of optimal pump function